成都平原农田镉污染情况及油菜镉吸收特征

Characteristics of cadmium uptake by rape(B.junica) grown in cadmium contaminated farmland on Chengdu Plain

为了解成都平原农田镉污染现状及油菜对农田土壤镉的吸收特征,在成都平原镉污染农田选取45个样点,通过田间实地取样的方法,研究了32个品种油菜的镉吸收特征及其生长农田土壤镉污染特征。结果表明:45个取样点中有19个样点土壤镉含量超过土壤环境质量标准农业用地二级污染标准,除广汉外,其余各市区农田土壤都存在镉污染威胁,尤以什邡为重;土壤有效镉含量随全镉含量增加而递增,两者呈极显著线性正相关;土壤镉污染生物有效性系数随土壤pH值升高而降低,两者呈极显著线性负相关。试验所用油菜对土壤镉均有一定吸收累积作用,且不同品种差异显著;同一品种油菜镉富集能力主要受土壤镉含量的影响;绿星油99(德阳)、821(绵竹)、德油5号(彭州)和德油4号(什邡)分别为各市区筛选出的具有较强镉富集能力的适栽品种,也是试验中发现的最适合各市区作为农田镉污染修复植物的油菜品种。油菜籽粒镉富集能力主要受茎秆镉含量的影响,且在镉存赋能力的品种差异上均表现为茎秆大于籽粒。

To understand the current situation of farmlands suffering from cadmium（Cd） contamination and that associated with Cd uptake characteristics of rape grown on Chengdu Plain, forty five soil samples were taken from the Cd contaminated farmland areas and thirty two rape cultivars were selected to study their growth and Cd uptake characteristics under soil Cd stress.The results showed that soil Cd contents in nineteen over forty five soil samples surpassed the Soil Environmental Quality Standards For Soils（Farmland Class Ⅱ）. Farmlands in all the counties/cities under investigation（except Guanghan city） existed threat of Cd contamination, particularly in Shifang City. Contents of soil available Cd increased with an increase in soil total Cd and both significantly correlated with each other. On the contrary, the Cd bioavailability decreased with an increase in soil pH, showing a highly negative correlation between the two. All the rape cultivars tested showed an accumulative feature to soil Cd but the accumulative ability varied considerably among cultivars. To a given cultivar, its Cd accumulative ability mainly depended on soil total Cd contents. Several high Cd-accumulative cultivars were identified from the screening study including Lüxingyou in Deyang, 821 in Mianzhu, Deyou 5 in Pengzhou and Deyou 4 in Shifang, which are highly suitable to grow in the selected Cd contaminated areas as potential phytoremediators. Cd accumulation ability of the rape seeds was mainly affected by Cd contents in the stalk, and thus, the differences of Cd accumulation ability among cultivars depended more on stalk than on seeds.